/*
* Copyright 1997, Regents of the University of Minnesota
*
* separator.c
*
* This file contains code for separator extraction
*
* Started 8/1/97
* George
*
* $Id: separator.c,v 1.1 1998/11/27 17:59:30 karypis Exp $
*
*/
#include <metis.h>
/*************************************************************************
* This function takes a bisection and constructs a minimum weight vertex
* separator out of it. It uses the node-based separator refinement for it.
**************************************************************************/
void ConstructSeparator(CtrlType *ctrl, GraphType *graph, float ubfactor)
{
long i, j, k, nvtxs, nbnd;
idxtype *xadj, *where, *bndind;
nvtxs = graph->nvtxs;
xadj = graph->xadj;
nbnd = graph->nbnd;
bndind = graph->bndind;
where = idxcopy(nvtxs, graph->where, idxwspacemalloc(ctrl, nvtxs));
/* Put the nodes in the boundary into the separator */
for (i=0; i<nbnd; i++) {
j = bndind[i];
if (xadj[j+1]-xadj[j] > 0) /* Ignore islands */
where[j] = 2;
}
GKfree(&graph->rdata, LTERM);
Allocate2WayNodePartitionMemory(ctrl, graph);
idxcopy(nvtxs, where, graph->where);
idxwspacefree(ctrl, nvtxs);
ASSERT(IsSeparable(graph));
Compute2WayNodePartitionParams(ctrl, graph);
ASSERT(CheckNodePartitionParams(graph));
FM_2WayNodeRefine(ctrl, graph, ubfactor, 8);
ASSERT(IsSeparable(graph));
}
/*************************************************************************
* This function takes a bisection and constructs a minimum weight vertex
* separator out of it. It uses an unweighted minimum-cover algorithm
* followed by node-based separator refinement.
**************************************************************************/
void ConstructMinCoverSeparator0(CtrlType *ctrl, GraphType *graph, float ubfactor)
{
long i, ii, j, jj, k, l, nvtxs, nbnd, bnvtxs[3], bnedges[2], csize;
idxtype *xadj, *adjncy, *bxadj, *badjncy;
idxtype *where, *bndind, *bndptr, *vmap, *ivmap, *cover;
nvtxs = graph->nvtxs;
xadj = graph->xadj;
adjncy = graph->adjncy;
nbnd = graph->nbnd;
bndind = graph->bndind;
bndptr = graph->bndptr;
where = graph->where;
vmap = idxwspacemalloc(ctrl, nvtxs);
ivmap = idxwspacemalloc(ctrl, nbnd);
cover = idxwspacemalloc(ctrl, nbnd);
if (nbnd > 0) {
/* Go through the boundary and determine the sizes of the bipartite graph */
bnvtxs[0] = bnvtxs[1] = bnedges[0] = bnedges[1] = 0;
for (i=0; i<nbnd; i++) {
j = bndind[i];
k = where[j];
if (xadj[j+1]-xadj[j] > 0) {
bnvtxs[k]++;
bnedges[k] += xadj[j+1]-xadj[j];
}
}
bnvtxs[2] = bnvtxs[0]+bnvtxs[1];
bnvtxs[1] = bnvtxs[0];
bnvtxs[0] = 0;
bxadj = idxmalloc(bnvtxs[2]+1, "ConstructMinCoverSeparator: bxadj");
badjncy = idxmalloc(bnedges[0]+bnedges[1]+1, "ConstructMinCoverSeparator: badjncy");
/* Construct the ivmap and vmap */
ASSERT(idxset(nvtxs, -1, vmap) == vmap);
for (i=0; i<nbnd; i++) {
j = bndind[i];
k = where[j];
if (xadj[j+1]-xadj[j] > 0) {
vmap[j] = bnvtxs[k];
ivmap[bnvtxs[k]++] = j;
}
}
/* OK, go through and put the vertices of each part starting from 0 */
bnvtxs[1] = bnvtxs[0];
bnvtxs[0] = 0;
bxadj[0] = l = 0;
for (k=0; k<2; k++) {
for (ii=0; ii<nbnd; ii++) {
i = bndind[ii];
if (where[i] == k && xadj[i] < xadj[i+1]) {
for (j=xadj[i]; j<xadj[i+1]; j++) {
jj = adjncy[j];
if (where[jj] != k) {
ASSERT(bndptr[jj] != -1);
ASSERTP(vmap[jj] != -1, ("%ld %ld %ld\n", jj, vmap[jj], graph->bndptr[jj]));
badjncy[l++] = vmap[jj];
}
}
bxadj[++bnvtxs[k]] = l;
}
}
}
ASSERT(l <= bnedges[0]+bnedges[1]);
MinCover(bxadj, badjncy, bnvtxs[0], bnvtxs[1], cover, &csize);
IFSET(ctrl->dbglvl, DBG_SEPINFO,
printf("Nvtxs: %6ld, [%5ld %5ld], Cut: %6ld, SS: [%6ld %6ld], Cover: %6ld\n", nvtxs, graph->pwgts[0], graph->pwgts[1], graph->mincut, bnvtxs[0], bnvtxs[1]-bnvtxs[0], csize));
for (i=0; i<csize; i++) {
j = ivmap[cover[i]];
where[j] = 2;
}
GKfree(&bxadj, &badjncy, LTERM);
for (i=0; i<nbnd; i++)
bndptr[bndind[i]] = -1;
for (nbnd=i=0; i<nvtxs; i++) {
if (where[i] == 2) {
bndind[nbnd] = i;
bndptr[i] = nbnd++;
}
}
}
else {
IFSET(ctrl->dbglvl, DBG_SEPINFO,
printf("Nvtxs: %6ld, [%5ld %5ld], Cut: %6ld, SS: [%6d %6d], Cover: %6d\n", nvtxs, graph->pwgts[0], graph->pwgts[1], graph->mincut, 0, 0, 0));
}
idxwspacefree(ctrl, nvtxs);
idxwspacefree(ctrl, graph->nbnd);
idxwspacefree(ctrl, graph->nbnd);
graph->nbnd = nbnd;
ASSERT(IsSeparable(graph));
}
/*************************************************************************
* This function takes a bisection and constructs a minimum weight vertex
* separator out of it. It uses an unweighted minimum-cover algorithm
* followed by node-based separator refinement.
**************************************************************************/
void ConstructMinCoverSeparator(CtrlType *ctrl, GraphType *graph, float ubfactor)
{
long i, ii, j, jj, k, l, nvtxs, nbnd, bnvtxs[3], bnedges[2], csize;
idxtype *xadj, *adjncy, *bxadj, *badjncy;
idxtype *where, *bndind, *bndptr, *vmap, *ivmap, *cover;
nvtxs = graph->nvtxs;
xadj = graph->xadj;
adjncy = graph->adjncy;
nbnd = graph->nbnd;
bndind = graph->bndind;
bndptr = graph->bndptr;
where = graph->where;
vmap = idxwspacemalloc(ctrl, nvtxs);
ivmap = idxwspacemalloc(ctrl, nbnd);
cover = idxwspacemalloc(ctrl, nbnd);
if (nbnd > 0) {
/* Go through the boundary and determine the sizes of the bipartite graph */
bnvtxs[0] = bnvtxs[1] = bnedges[0] = bnedges[1] = 0;
for (i=0; i<nbnd; i++) {
j = bndind[i];
k = where[j];
if (xadj[j+1]-xadj[j] > 0) {
bnvtxs[k]++;
bnedges[k] += xadj[j+1]-xadj[j];
}
}
bnvtxs[2] = bnvtxs[0]+bnvtxs[1];
bnvtxs[1] = bnvtxs[0];
bnvtxs[0] = 0;
bxadj = idxmalloc(bnvtxs[2]+1, "ConstructMinCoverSeparator: bxadj");
badjncy = idxmalloc(bnedges[0]+bnedges[1]+1, "ConstructMinCoverSeparator: badjncy");
/* Construct the ivmap and vmap */
ASSERT(idxset(nvtxs, -1, vmap) == vmap);
for (i=0; i<nbnd; i++) {
j = bndind[i];
k = where[j];
if (xadj[j+1]-xadj[j] > 0) {
vmap[j] = bnvtxs[k];
ivmap[bnvtxs[k]++] = j;
}
}
/* OK, go through and put the vertices of each part starting from 0 */
bnvtxs[1] = bnvtxs[0];
bnvtxs[0] = 0;
bxadj[0] = l = 0;
for (k=0; k<2; k++) {
for (ii=0; ii<nbnd; ii++) {
i = bndind[ii];
if (where[i] == k && xadj[i] < xadj[i+1]) {
for (j=xadj[i]; j<xadj[i+1]; j++) {
jj = adjncy[j];
if (where[jj] != k) {
ASSERT(bndptr[jj] != -1);
ASSERTP(vmap[jj] != -1, ("%ld %ld %ld\n", jj, vmap[jj], graph->bndptr[jj]));
badjncy[l++] = vmap[jj];
}
}
bxadj[++bnvtxs[k]] = l;
}
}
}
ASSERT(l <= bnedges[0]+bnedges[1]);
MinCover(bxadj, badjncy, bnvtxs[0], bnvtxs[1], cover, &csize);
IFSET(ctrl->dbglvl, DBG_SEPINFO,
printf("Nvtxs: %6ld, [%5ld %5ld], Cut: %6ld, SS: [%6ld %6ld], Cover: %6ld\n", nvtxs, graph->pwgts[0], graph->pwgts[1], graph->mincut, bnvtxs[0], bnvtxs[1]-bnvtxs[0], csize));
for (i=0; i<csize; i++) {
j = ivmap[cover[i]];
where[j] = 2;
}
GKfree(&bxadj, &badjncy, LTERM);
}
else {
IFSET(ctrl->dbglvl, DBG_SEPINFO,
printf("Nvtxs: %6ld, [%5ld %5ld], Cut: %6ld, SS: [%6d %6d], Cover: %6d\n", nvtxs, graph->pwgts[0], graph->pwgts[1], graph->mincut, 0, 0, 0));
}
/* Prepare to refine the vertex separator */
idxcopy(nvtxs, graph->where, vmap);
GKfree(&graph->rdata, LTERM);
Allocate2WayNodePartitionMemory(ctrl, graph);
idxcopy(nvtxs, vmap, graph->where);
idxwspacefree(ctrl, nvtxs+2*graph->nbnd);
Compute2WayNodePartitionParams(ctrl, graph);
ASSERT(CheckNodePartitionParams(graph));
FM_2WayNodeRefine_OneSided(ctrl, graph, ubfactor, 6);
ASSERT(IsSeparable(graph));
}
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